1. Field of the Invention
This invention relates to doors pre-hung on door frames and in particular it relates to a door retainer for maintaining a door in closed position relative to the door frame.
2. Background of the Invention
Pre-hung door shops and certain manufacturers supply doors pre-hung on door jambs. The door jambs include two vertical side jambs which will be referred to as a hinge jamb and a strike jamb and a header fitted across the top between the side jambs. Heavier exterior doors may have a temporary strip or permanent sill fastened across the bottom of the jambs. The door and door jambs are prepped for the installation of lock sets, but are not fitted with the knobs, striker plates, latches and such since there are unlimited models and configurations from which a user may choose. The doors are attached to the hinge jamb by hinges and the assembly requires a fastener to hold the door in a "closed" position relative to the door jambs during transport or shipment. If the door is not secured to the door jambs in a closed position, the door jamb is readily damaged. The door is preferably secured tightly to the strike jamb so that no relative movement will occur during shipment. Any movement will of course cause a rubbing action between the door and strike jamb which will likely cause damage to the surface of the door and jamb or at least leave unsightly marks. Current practice is to drive nails through the strike jamb into the edge of the door to securely hold the door during shipping from point of manufacture to point of installation. The nails utilized are typically double headed to facilitate removal.
The use of nails is undesirable. The nails, which will later be removed, leave holes in the edge of the door and face of the strike jamb, which must be filled, sanded and finished. The pre-hung door units are often pre-finished prior to shipment to a user. The prehung door unit is often prefinished by a separate vendor. The vendor must remove the nails in order to finish all sides of the door and door jambs. When the finishing operation is completed, the door is once again secured to the door jambs by driving in another set of nails. This requires that the newly created nail holes also must be filled and finished at the site of the door installation. Additionally, the nails driven in through the strike jamb may on occasion cause splitting of the door jamb or edge of the door. The double headed nails protrude from the surface of the backside of the door jambs and may cause damage to adjacent doors or casings during shipment. Avoiding the use of such fasteners is therefor an object of the present invention.
The present invention utilizes the door prep for accommodating a specially designed fastener that doesn't deface the door and door jamb. The door prep referred to includes a standard face bore and edge bore in the door for mounting lock sets, i.e., a door knob assembly. The strike jamb prep of the door jamb includes a bore for receiving the latch of the lock assembly. The face bore (see FIG. 1, item 30 of drawings) of the door has been standardized at 21/8 inch diameter and is backset from the edge of the door a distance of either 23/8 inches or 23/4 inches. The backset is measured from the edge of the door to the center of the face bore. The edge bore (see FIG. 1, item 32 of drawings) has been standardized at one inch diameter and extends from the edge of the door to the face bore. The bore in the strike jamb (see FIG. 1, item 34 of drawings) is provided as either a one inch diameter circular bore or a rectangular 3/4 by 1 inch bore. There are variations to the above, but they are considered special and account for a very small percentage of the doors that are pre-hung.
Retainers utilizing the door prep have been developed as demonstrated by U.S. Pat. No. 319,007. The illustrated retainer includes a plug and bolt fastener. The plug is insertable into the edge bore of the door via the face bore. The plug is substantially cylindrical having a diameter to fit snugly in the edge bore of the door. One end of the plug is reduced or flattened in width for a short distance so that it will fit into either the circular or the rectangular bore of the strike jamb. The opposite end of the plug has extended curved ears that will engage the arc surface of the face bore inside the door to limit the plugs entry into the edge bore of the door. A washer head type threaded fastener is inserted through the back side of the bore in the strike jamb and threadably engages the plug to secure the door to the strike jamb.
The described retainer has a number of deficiencies. It is preferable to have the plug of sufficient length to extend into the bore in the strike jamb. It has been found that the barrel length of this prior plug design, of necessity, must be limited in order to insert the plug into the edge bore of the door via the face bore. The barrel length must be short enough so that the plug will "go around the corner" as it is inserted. The extending ears, which conform to the arc of the face bore, limits the overall length of the plug since they must clear the edge of the face bore at the door's surface as the plug is inserted. The limited length does not permit the end of the plug to extend into the bore of the jamb when the cross bore is backset 23/4 inches. It is, therefore, desirable to have a plug of sufficient length to extend into the bore of the strike jamb to make a rigid interconnection between the door and the strike jamb for either 23/8 or 23/4 inches backset dimension.
Convenience of assembly is another factor. Extra seconds required to maneuver the plug into and out of the edge bore is to be avoided. The prior device was so tightly dimensioned that an assembler often had such difficulty. Also, the threaded fastener required additional seconds to screw on and screw off of the plug.